In March, high temperatures over two-thirds of the continental US set numerous records and made it the nation's warmest March on record. April has been no slouch either, as high temperature records have continued to fall. But at the time of our last report, the services that track global temperatures hadn't analyzed the global extent of the warmth. Now that the numbers for March and April are available, it's clear that the rest of the globe generally hasn't shared the US's record heat.

Globally, the current period of warming began back in the 1970s. NASA's GISTEMP tracks the current global temperature against a baseline established by the 1951-1980 average, and it hasn't seen a calendar year below that average since 1976, or a month below it since 1994. The US climate has generally reflected that, with high temperature extremes dominating over the last several decades, as shown below.

http://cdn.arstechnica.net//wp-conte...mpExtremes.pngTrends in temperature extremes in the continental US show that 2012 has been exceptionally warm.NOAA
That said, the US is a relatively small portion of the global land mass, and an even smaller portion of the planet's total surface area. It's entirely possible to have the US experiencing extreme temperatures without the planet as a whole really noticing. And that's what has seemed to have happened this spring. Even as the US has experienced record-breaking extremes, the GISSTEMP index has seen global temperatures that were roughly equivalent to the ones we experienced last year, and well below those of 2010, the warmest year on record.